An endoscope is a piece of surgical equipment that has imaging capabilities so as to be able to provide images of an internal body cavity of a patient. Most minimally invasive surgical procedures performed in the gastrointestinal (GI) tract or other internal body cavities are accomplished with the aid of an endoscope. An endoscope typically includes one or more instrument channels through which other medical catheters/instruments can pass.
Typically, an endoscope is used to reach an area of interest within a body cavity and, thereafter, another instrument such as a surgical catheter is extended through the instrument channel of the endoscope to perform some desired procedure. In a pulmonary endoscopic procedure, one of the key characteristics of the endoscope is its outer diameter with respect to the bronchial tree through which it must pass. For example, a conventional bronchoscope is typically a two or three lumen structure that includes fiber optic bundles for imaging and illumination and an instrument channel for the application of suction and/or the placement of tools. A conventional bronchoscope typically has an instrument channel lumen with an internal diameter of about 2.0 mm to 2.8 mm, and an outer shaft diameter of approximately 5 or 6 millimeters. Such an endoscope is too large to navigate the bronchial branches of the periphery of the lung, which are typically in the range of 2 to 3 millimeters wide. As a consequence, a conventional bronchoscope can only reach about the third or fourth bifurcation level of the bronchial tree. If a tissue biopsy is needed at the periphery of the tree where it is too narrow for the bronchoscope to access, the biopsy forceps are often pushed blindly into the region of the tissue and the sample is obtained in the absence of visualization.
Another factor that complicates endoscopic exploration of the periphery of the lung is the complexity and number of bronchial branches that exist. Electromagnetic navigation systems have been developed by companies such as SuperDimension® (Minneapolis, Minn.) and Mediguide® (Arlington, Va.) that allow for guided access to peripheral sites in the airways. The current navigation systems are limited, however, by the lack of means for directly visualizing the patient's anatomy at the distal location of the extended working channel. This lack of direct visualization may result in inaccurate initial targeting of a therapeutic site, such as a biopsy site, without any indication of whether the correct target tissue has been reached, due in part to tolerance issues on how accurate these systems can be. Also, a subsequent event such as patient movement or coughing may modify the target site after the sensor is removed from the working channel.
Therefore, to improve access to remote locations in the body there is a need for a small diameter visualization catheter with a working channel that can be used in conjunction with electromagnetic tracking.